From DE 199 34 696 A1 a drive-train of a hybrid vehicle is known, which drive-train comprises an internal combustion engine and an electric machine. In addition the drive-train known from this prior art comprises a transmission connected between the drive aggregate and a drive output of the drive-train, the internal combustion engine, the electric machine and the transmission being coupled to one another by means of a device comprising a planetary gear system and a clutch. The planetary gear system comprises as elements a ring gear, a sun gear and a carrier, wherein two of these three elements of the planetary gear system can be coupled by means of the clutch, which then serves as a bridging clutch. Such a drive-train of a hybrid vehicle is also referred to as an electro-dynamic drive system.
With such a drive system a defined range of functions can be implemented with a drive-train of a hybrid vehicle. However, there is a need to extend the functional range of such a drive-train.